Cathode belt structure for use in a metal-air fuel cell battery system and method of fabricating the same

ABSTRACT

In an air-metal fuel cell battery (FCB) system, wherein metal-fuel tape, the ionically-conductive medium and the cathode structures are transported at substantially the same velocity at the locus of points at which the ionically-conductive medium contacts the moving cathode structure and the moving metal-fuel tape during discharging and recharging modes of operation. In a first generalized embodiment of the present invention, the ionically-conductive medium is realized as an ionically-conductive belt, and the metal-fuel tape, ionically-conductive belt, and movable cathode structure are transported at substantially the same velocity at the locus of points which the ionically-conducing belt contacts the metal-fuel tape and the cathode structure during system operation. In a second generalized embodiment of the present invention, the ionically-conductive medium is realized as a solid-state (e.g. gelatinous) film layer integrated with the metal-fuel tape, and the metal-fuel tape, ionically-conductive film layer and movable cathode structure are transported at substantially the same velocity at the locus of points which the ionically-conducing film layer contacts the metal-fuel tape and the cathode structure during system operation. In a third generalized embodiment of the present invention, the ionically-conductive medium is realized as a solid-state film layer integrated with the movable cathode structure, and the metal-fuel tape, ionically-conductive film layer and movable cathode structure are transported at substantially the same velocity at the locus of points which the ionically-conducing film layer contacts the metal-fuel tape and the cathode structure during system operation. By transporting the movable cathode structure, ionically contacting medium and metal-fuel tape within the system as described above, generation of frictional forces among such structures are minimized during system operation, and thus the damage to the cathode structure and metal-fuel tape is substantially reduced.

RELATED CASES

Continuation of copending application Ser. No. 09/110,762 entitled“Metal-Air Fuel Cell Battery System Employing Metal Fuel Tape AndLow-Friction Cathode Structures” filed Jul. 3, 1998, which is aContinuation-in-Part of: copending application Ser. No. 09/074,337entitled “Metal-Air Fuel-Cell Battery Systems” filed May 7, 1998; andcopending application Ser. No. 08/944,507 entitled “High-Power DensityMetal-Air Fuel Cell Battery System” by Sadeg Faris, et al. filed Oct. 6,1997, said application being assigned to Reveo, Inc. and incorporatedherein by reference in its entirety.

BACKGROUND OF INVENTION

1. Field of Invention

The present invention relates to metal-air fuel cell battery systemsdesigned to produce electrical power from metal-fuel tape transportedover the cathode structures of the system, and more particularly to suchsystems employing movable cathode structures having low frictioncharacteristics.

2. Brief Description of the Prior Art

In copending U.S. application Ser. No. 08/944,507 entitled “High-PowerDensity Metal-Air Fuel Cell Battery System, Applicants disclose severaltypes of novel metal-air fuel cell battery (FCB) systems. During powergeneration, metal-fuel tape is transported over a stationary cathodestructure in the presence of an ionically-conductive medium, such as anelectrolyte-impregnated gel (i.e. electrolyte-impregnated film). Inaccordance with well known principles of electrochemistry, thetransported metal-fuel tape is oxidized as electrical power is producedfrom the system.

FCB power generation systems of the type disclosed in U.S. applicationSer. No. 08/944,507 have numerous advantages over prior artelectro-chemical power generation devices including, for example, thegeneration of electrical power over a range of output voltage levelsselectable to particular electrical load conditions. Also, the oxidizedmetal-fuel tape can be reconditioned (i.e. recharged) during batterycharging cycles carried out during electrical power generation, as wellas separately therefrom.

In copending application Ser. No. 09/074,337 entitled “Metal-AirFuel-Cell Battery Systems” filed May 7, 1998, Applicants discloseseveral novel systems and methods for reconditioning oxidized metal-fueltape used in FCB systems. In theory, such technological improvementsenable metal-fuel tape to be quickly recharged in an energy efficientmanner for reuse in electrical power generation cycles. Such advancesoffer great promise in many fields of endeavor requiring electricalpower.

The greatest limitation, however, with prior art metal-air FCB systemsis that, as the metal-fuel tape is being transported over the stationarycathode structures within such systems, frictional (e.g. shear) forcesare generated, causing a number of problems to arise.

One problem is that such frictional forces cause an increase in theamount of electrical power required to transport the metal-fuel tapethrough the system.

Another problem is that such frictional forces cause metal-oxideparticles to be shed from metal-fuel tape during transport and to becomeembedded within the porous structure of the cathode, thereby preventingionic transport between the cathode and ionically-conductive medium(i.e. referred to as “blinding”), and increasing the likelihood ofdamage (or destruction) to the surface of the cathode structure andmetal-fuel tape.

Overall, such problems tend to reduce the operational efficiency ofprior art metal-air FCB systems, as well as the life of the cathodestructures and metal-fuel tape employed therein.

Thus, there is a great need in the art for an improved metal-air fuelcell battery system which avoids the shortcomings and drawbacks of priorart systems and methodologies.

OBJECTS AND SUMMARY OF THE INVENTION

Accordingly, it is a primary object of the present invention to providean improved metal-air fuel cell battery (FCB) system which avoids theshortcomings and drawbacks of prior art systems and methodologies.

Another object of the present invention is to provide such a system,wherein both the metal-fuel tape, ionically-conductive medium andcathode structures are moved relative to each other during systemoperation in order to reduce frictional (e.g. shear) forces generated byrelative movement among the cathode structure(s), metal-fuel tape andionically-conductive medium during system operation.

Another object of the present invention is to provide such a system,wherein this reduction in frictional forces results in: a reduction inthe amount of electrical power required to drive the cathodestructure(s), the metal-fuel tape and ionically-conductive medium duringsystem-operation; a reduction in the shedding of metal-oxide particlesfrom metal-fuel tape and the embedding of such particles within theporous structure of the cathode; and a decrease the likelihood of damageto the cathode structures and metal-fuel tape employed in the system.

Another object of the present invention is to provide such metal-airfuel cell battery system, wherein a transport mechanism is used totransport the cathode structures, ionically-conductive medium andmetal-fuel tape at substantially the same velocity at the locus ofpoints at which the ionically-conductive medium contacts both themetal-fuel tape and the cathode structures during system operation inorder to minimize the generation of frictional forces between themovable cathode structures, metal-fuel tape and ionically-conductivemedium.

Another object of the present invention is to provide such a system,wherein velocity control of the metal-fuel tape, cathode structures andionically-conducting medium can be realized in a variety of differentways.

Another object of the present invention is to provide such a system,wherein the cathode structure is realized as a rotating cathode cylinderhaving fine perforations formed in the surface thereof and a hollowcentral core which enables the transport of oxygen to the interfacebetween the ionically-conductive medium and metal-fuel tape transportedthereover.

Another object of the present invention is to provide such a system,wherein the cylindrical cathode comprises a plastic hollow cylinderabout which is attached is a cathode element made from nickel meshfabric, for current collection, embedded within carbon, catalytic andbinder material.

Another object of the present invention is to provide such a system,wherein the cylindrical cathode is rotated at a controlled angularvelocity and the metal-fuel tape is transported over the surface of therotating cathode so that both the metal-fuel tape and the cathodestructure move at substantially the same velocity at the locus of pointsat which the ionically-conducing medium contacts both the metal-fueltape and the cathode structure.

Another object of the present invention is to provide such a system,wherein the ionically-conductive medium is realized in the form of anionically-conductive belt, transported (i.e. running) between two ormore transport cylinders.

Another object of the present invention is to provide such a system,wherein the ionically-conductive belt is fabricated from an open-cellplastic material impregnated with an ionically-conductive material whichenables ionic transport between the cathode and anode structures of thesystem.

Another object of the present invention is to provide such a system,wherein velocity control can be achieved in a variety of ways, forexample: by driving the cylindrical cathode structure with a belt thatis also used to transport the metal-fuel tape (i.e. between supply andtake-up reels or hubs within a cassette type-device); or by driving thecylindrical cathode structure and supply and take-up hubs of a fuelcassette device using a set of speed controlled motors, or spring-drivenmotors.

Another object of the present invention is to provide such a system,wherein the ionically-conductive medium is realized as a solid-state(e.g. gel-like) film applied on the outer surface of the cylindricalcathode structure, and the metal-fuel tape is realized in the form ofthin zinc tape, zinc power mixed with an binder and carried on apolyester substrate, or zinc powder impregnated within the substrate ofthe tape itself.

Another object of the present invention is to provide metal-air fuelcell battery system, wherein the rotatable cathode structure is realizedas a cathode belt structure having ultrafine perforations in the surfacethereof and a hollow central core for enabling oxygen transport to theinterface between the ionically-conductive medium and the metal-fueltape transported thereover.

Another object of the present invention is to provide such a system,wherein the cathode belt structure comprises an open-cell type plasticsubstrate, within which nickel mesh fabric is embedded with carbon andcatalytic material.

Another object of the present invention is to provide such a system,wherein during system operation, the cathode belt structure istransported at a controlled velocity between two or more transportcylinders, while metal-fuel tape is transported over the surface of thecathode belt structure at substantially the same velocity at the locusof points at which the ionically-conducing medium contacts both themetal-fuel tape and the cathode structure.

Another object of the present invention is to provide such a system,wherein the ionically-conductive medium of the system is realized in theform of an ionically-conductive belt structure transported between themetal-fuel tape and the cathode belt structure at substantially the samevelocity as the cathode belt structure and metal-fuel tape at the locusof points at which the ionically-conducing medium contacts both themetal-fuel tape and the cathode structure.

Another object of the present invention is to provide such a system,wherein the ionically-conductive medium of the system is realized in theform of a thin-film integrated with the outer surface of the cathodebelt structure so as to establish contact with the anodicmetal-fuel-tape transported thereover.

Another object of the present invention is to provide such a system,wherein the metal-fuel tape is realized in the form of thin zinc tape,zinc power mixed with an binder and carried on a polyester or likesubstrate, or zinc powder impregnated within the substrate itself.

Another object of the present invention is to provide a metal-air FCBsystem, wherein the surface tension between the metal-fuel tape and theionically-conductive medium is sufficiently high (due to wetting of themetal-fuel tape, the ionically-conductive medium and the movable cathodestructures) in order to create hydrostatic drag (i.e. hydrostaticattraction) between the metal-fuel tape and the ionically-conductivebelt as well as between the cathode structure (e.g. cylinder or belt)and the ionically-conductive medium (e.g. belt or layer), therebyenabling coordinated movement among the metal-fuel tape, cathodestructure (e.g. cylinder or belt) and ionically-conductive medium (e.g.belt or layer), with minimal slippage.

Another object of the present invention is to provide a FCB systememploying hydrostatic drag between the metal-fuel tape and the ionicallyconductive medium and between the moving cathode structures and theionically conductive medium so that all three of these movable systemcomponents can be transported (or moved) within the system by moving oneor more of such system components (e.g. using spring-driven motor)thereby simplifying and reducing the cost of the system.

Another object of the present invention is to provide a system, whereinthe metal-fuel tape, cathode structures and ionically-conductive mediumare moved relative to each other so that frictional forces generatedamong the metal-fuel tape, cathode structures and ionically-conductivemedium are substantially reduced, thereby reducing the amount ofelectrical power required to drive the cathode, metal-fuel tape andionically-conductive medium and transport mechanisms, and decreasing thelikelihood of damage to the cathode structure and metal-fuel tape, andpermit reuse thereof over a large number of cycles without replacement.

These and other objects of the present invention will become apparenthereinafter and in the claims to invention.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the Objects of the PresentInvention, the following detailed Description of the IllustrativeEmbodiments Of the Present Invention should be read in conjunction withthe accompanying Drawings, wherein:

FIG. 1A is a schematic representation of a first generalized embodimentof the metal-air fuel-cell battery (FCB) system of the presentinvention, wherein the ionically-conductive medium is a viscouselectrolyte that is free to move at the same velocity as the metal-fueltape and cathode structure(s) of the system, at the locus of points atwhich the ionically-conducing medium contacts the metal-fuel tape andthe cathode structure during system operation:

FIG. 1B is a schematic representation of a second generalized embodimentof the (FCB) system of the present invention, wherein theionically-conductive medium is integrated with the metal-fuel tape andtransported at substantially the same velocity as the cathode structureat the locus of points at which the ionically-conducing medium contactsthe metal-fuel tape and the cathode structure during system operation;

FIG. 1C is a schematic representation of a third generalized embodimentof the system of the present invention, wherein the ionically-conductivemedium is integrated with the cathode structure, and transported atsubstantially the same velocity as the metal-fuel tape at the locus ofpoints at which the ionically-conducing medium contacts the metal-fueltape and the cathode structure during system operation;

FIG. 2 is a first illustrative embodiment of the FCB system, whereinmetal-fuel tape is passed over a rotating cathode cylinder having anionically-conductive coating (e.g. gelatinous or solid-state film)applied thereover, and wherein the anode-contacting structure of thesystem engages the inner surface of the metal-fuel tape;

FIG. 2A is a partially broken away perspective view of the cylindricalcathode structure of the present invention shown in FIG. 2, in which anionically-conductive film layer is applied over the outer surfacethereof;

FIG. 2B is a cross-sectional view of the cylindrical cathode structureshown in FIG. 2, taken along the line 2B—2B of FIG. 2A;

FIG. 2C is cross-sectional view of a section of the metal-fuel tapeshown used in the system of FIG. 2C;

FIG. 3 is a second illustrative embodiment of the FCB system, whereinmetal-fuel tape is passed over a second embodiment of the cylindricalcathode structure hereof which is driven an angular velocity equalizedto the velocity of the metal-fuel tape, and wherein the anode-contactingstructure engages the inner surface of the metal-fuel tape and themetal-fuel tape has an ionically-conductive coating applied thereon;

FIG. 3A is a partially broken away perspective view of the cylindricalcathode structure of the present invention shown in FIG. 3, in which thecathode structure thereof is exposed to the ambient environment;

FIG. 3B is a cross-sectional view of the cylindrical cathode structureshown in FIG. 3, taken along the line 3B—3B of FIG. 3A;

FIG. 3C1 is cross-sectional view of a section of a first type ofmetal-fuel tape that can be used in the system of FIG. 3C, showing anionically-conductive film layer applied to the surface of a thin layerof metal fuel;

FIG. 3C2 is cross-sectional view of a section of a second type ofmetal-fuel tape that can be used in the system of FIG. 3C, showing asubstrate material embodying an ionically-conductive medium andmetal-fuel particles;

FIG. 4 is a third illustrative embodiment of the FCB system, in whichmetal-fuel tape is passed over the cylindrical cathode structure hereofdriven an angular velocity equalized to the velocity of the metal-fueltape and having an ionically-conductive coating applied thereover, andwherein the anode-contacting structure engages the outer surface of themetal-fuel tape;

FIG. 4A is a partially broken away perspective view of the cylindricalcathode structure of the present invention shown in FIG. 4, in which thecathode structure thereof has an ionically-conductive coating appliedthereover;

FIG. 4B is a cross-sectional view of the cylindrical cathode structureshown in FIG. 3, taken along the line 4B—4B of FIG. 4A;

FIG. 4C is cross-sectional view of a section of metal-fuel tape that canbe used in the system of FIG. 4C;

FIG. 5 is a fourth illustrative embodiment of the FCB system, in whichmetal-fuel tape is passed over a fourth embodiment of the cylindricalcathode structure hereof driven at an angular velocity equalized to thevelocity of the metal-fuel tape, and wherein the anode contactingstructure engages the outer surface of the metal-fuel tape and themetal-fuel tape has an ionically-conductive coating applied thereon;

FIG. 5A is a partially broken away perspective view of the cylindricalcathode structure of the present invention shown in FIG. 5, in which thecathode structure thereof is exposed to the ambient environment;

FIG. 5B is a cross-sectional view of the cylindrical cathode structureshown in FIG. 5, taken along the line 5B—5B of FIG. 5A;

FIG. 5C1 is cross-sectional view of a section of a first type ofmetal-fuel tape that can be used in the system of FIG. 5C, showing anionically-conductive film layer applied to the surface of a thin layerof metal fuel;

FIG. 5C2 is cross-sectional view of a section of second type ofmetal-fuel tape that can be used in the system of FIG. 5C, showing anionically-conductive medium embodied within a substrate materialembodying metal-fuel particles;

FIG. 6 is a fifth illustrative embodiment of the FCB system, whereinmetal-fuel tape is passed over the second embodiment of the cylindricalcathode structure hereof which is driven an angular velocity equalizedto the velocity of the metal-fuel tape while an ionically-conductivebelt is transported between the metal-fuel tape and the cylindricalcathode structure, and wherein the anode-contacting structure engagesthe outer surface of the metal-fuel tape;

FIG. 6A is a cross-sectional view of the ionically-conductive beltstructure shown in FIG. 6;

FIG. 6B is a cross-sectional view of a section of a first type ofmetal-fuel tape that can be used in the system of FIG. 6, realized inthe form of thin layer of metal fuel;

FIG. 6C is a cross-sectional view of a section of a second type ofmetal-fuel tape that can be used in the system of FIG. 6, realized bydepositing metallic powder and binder on a substrate;

FIG. 6D is a across-sectional view of a section of a third type ofmetal-fuel tape that can be used in the system of FIG. 6, realized byimpregnating metallic powder within a substrate material;

FIG. 7 is a sixth illustrative embodiment of the FCB system, whereinmetal-fuel tape is transported over the ionically-conductive solid-statefilm layer on a cathode belt structure, at substantially the samevelocity as the cathode belt structure at the locus of points at whichthe ionically-conductive film layer contacts both the cathode beltstructure and the metal-fuel tape, and wherein the anode-contactingstructure engages the outer surface of the metal-fuel tape between thecylindrical support structure and the cathode-contacting structure isdisposed opposite the anode support structure and engages the innersurface of the cathode belt structure;

FIG. 7A is a cross-sectional view of the cathode belt structure shown inFIG. 7;

FIG. 7B is cross-sectional view of a section of a first type ofmetal-fuel tape that can be used in the system of FIG. 7, realized inthe form of thin layer of metal fuel;

FIG. 7C is cross-sectional view of a section of a second type ofmetal-fuel tape that can be used in the system of FIG. 7, realized bydepositing metallic powder and binder on a substrate;

FIG. 7D is cross-sectional view of a section of a third type ofmetal-fuel tape that can be used in the system of FIG. 7, realized byimpregnating metallic powder within a substrate material;

FIG. 8 is a seventh illustrative embodiment of the FCB system, whereinmetal-fuel tape is transported over the ionically-conductive solid-statefilm layer on a cathode belt structure, at substantially the samevelocity as the cathode belt structure at the locus of points at whichthe ionically-conductive film layer contacts both the cathode beltstructure and the metal-fuel tap, and wherein the cathode-contactingstructure engages the outer surface of the cathode belt structurepassing over a cylindrical cathode roller and the anode-contactingstructure is disposed adjacent the cylindrical cathode roller andengages the inner surface of the cathode belt structure;

FIG. 8A is a cross-sectional view of the cathode belt structure shown inFIG. 8;

FIG. 8B is cross-sectional view of a section of a first type ofmetal-fuel tape that can be used in the system of FIG. 8, realized inthe form of thin layer of metal fuel;

FIG. 8C is cross-sectional view of a section of a second type ofmetal-fuel tape that can be used in the system of FIG. 8, realized bydepositing metallic powder and binder on a substrate;

FIG. 8D is cross-sectional view of a section of a third type ofmetal-fuel tape that can be used in the system of FIG. 8, realized byimpregnating metallic powder within a substrate material;

FIG. 9 is eight illustrative embodiment of the FCB system, whereinmetal-fuel tape having a solid-state ionically-conductive film layerapplied thereto is transported over a cathode belt structure atsubstantially the same velocity as the metal-fuel tape at the locus ofpoints at which the ionically-conductive film layer contacts both themetal-fuel tape and the cathode belt structure, and wherein theanode-contacting structure engages the outer surface of the metal-fueltape between the cathode belt transport cylinders and thecathode-contacting structure is disposed opposite the anode-contactingstructure between the cathode belt transport cylinders and engages theinner surface of the cathode belt structure;

FIG. 9A is a cross-sectional view of the cathode belt structure shown inFIG. 9;

FIG. 9B is a cross-sectional view of a section of a first type ofmetal-fuel tape that can be used in the system of FIG. 9, realized inthe form of thin layer of metal fuel carrying an ionically-conductivefilm layer;

FIG. 9C is a cross-sectional view of a section of a second type ofmetal-fuel tape that can be used in the system of FIG. 9, realized bymetallic powder and binder on a substrate carrying anionically-conductive layer;

FIG. 9D is a cross-sectional view of a section of a third type ofmetal-fuel tape that can be used in the system of FIG. 9, realized byimpregnating metallic powder within a substrate material carrying anionically conductive layer;

FIG. 10 is a ninth illustrative embodiment of the FCB system, whereinmetal-fuel tape is transported over an ionically-conductive belt whichis transported over a cathode belt structure at substantially the samevelocity at the locus of points at which the ionically-conductive beltcontacts both the metal-fuel tape and the cathode belt structure, andwherein the cathode-contacting structure engages the outer surface ofthe cathode belt structure passing over a cathode belt transportcylinder and the anode-contacting structure is disposed adjacent thecathode belt transport cylinder and engages the inner surface of thecathode belt structure;

FIG. 10A is a cross-sectional view of a first type of cathode beltstructure that can be used in the system shown in FIG. 10;

FIG. 10B is a cross-sectional view of a second type of cathode beltstructure that can be used in the system shown in FIG. 10;

FIG. 10C is cross-sectional view of a section of a first type ofmetal-fuel tape that can be used in the system of FIG. 10, realized inthe form of thin layer of metal fuel;

FIG. 10D is cross-sectional view of a section of a second type ofmetal-fuel tape that can be used in the system of FIG. 10, realized bydepositing metallic powder and binder on a substrate; and

FIG. 10E is cross-sectional view of a section of a third type ofmetal-fuel tape that can be used in the system of FIG. 8, realized byimpregnating metallic powder within a substrate material.

DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS OF THE PRESENTINVENTION

The present invention teaches transporting the metal-fuel tape, cathodestructure(s) and ionically-conductive medium in a metal-air FCB systemat substantially the same velocity at the locus of points at which theionically-conductive medium contacts the cathode structures and themetal-fuel tape. This condition of operation substantially reduces thegeneration of frictional (e.g. shear) forces among the metal-fuel tape,cathode structures and ionically-conductive medium. In turn, thisreduction in frictional (e.g shear) forces among such system componentsresults in a reduction in: the amount of electrical power required totransport the cathode structures, metal-fuel tape andionically-conductive medium during system operation; the shedding ofmetal-oxide particles from metal-fuel tape and the embedding of suchparticles within the porous structure of the cathode; and the likelihoodof damaging of the cathode structures and metal-fuel tape used in theFCB system. In FIGS. 1A through 1C, this principle of operation isschematically illustrated for three different FCB system designs.

A first generalized embodiment of the metal-air FCB system of thepresent invention is generally depicted by reference numeral 1 shown inFIG. 1A. In this generalized embodiment of the present invention, theionically-conductive medium (ICM) 2 is realized as a fluid or fluid-likesubstance which is free to move relative to both the metal-fuel tape 3and the cathode structure(s) 4 employed within the system, while themetal-fuel tape and cathode structure(s) are transported atsubstantially the same velocity at the locus of points which theionically-conducing medium contacts the metal-fuel tape and the cathodestructure during tape discharging and recharging cycles. As shown, acathode-contacting elements 5 establishes electrical contact withcathode structures 4 during system operation while an anode-contactingelement 6 establishes electrical contact with metal-fuel tape (i.e.anode) 3.

A second generalized embodiment of the metal-air FCB system of thepresent invention is generally depicted by reference numeral 1 and shownin FIG. 1B. In this generalized embodiment of the present invention, theionically-conductive medium 2 is integrated with the surface of themetal-fuel tape 3 (e.g. in the form of a (gelatinous or solid-state filmlayer applied thereto), while the metal-fuel tape 3,ionically-conductive medium 2 and cathode structure(s) 4 are transportedat substantially the same velocity at the locus of points at which theionically-conductive medium 2 contacts both the metal-fuel tape 3 andthe cathode structure 4 during system operation.

A third generalized embodiment of the metal-air fuel-cell battery (FCB)system of the present invention is shown in FIG. 1C, and generallydepicted by reference numeral 1. In this generalized embodiment of thepresent invention (e.g. in the form of a gelatinous or solid-state filmlayer applied thereto), while the metal-fuel tape 3,ionically-conductive medium 2, and cathode structure(s) 4 aretransported at substantially the same velocity at the locus of points atwhich the ionically-conducing medium contacts the metal-fuel tape andthe cathode structure during system operation.

There are various ways to realize the ionically-conductive medium ineach of these generalized embodiments of the FCB system. Also, there arevarious ways in which to achieve velocity control (i.e. velocityequalization) in each of these generalized system embodiments. Dependingon how the cathode structure is realized, the illustrative embodimentsof the present invention disclosed herein can be classified into one oftwo groups to simpify description of the corresponding FCB systems.

For example, in the first group of illustrative embodiments, shown inFIGS. 2 through 6D, the cathode structure is realized as a rotatablestructure of cylindrical geometry having fine perforations in thesurface thereof and a hollow central core enabling the transport of air(i.e. oxygen) to the interface between the metal-fuel tape andionically-conductive medium. In the second group of illustrativeembodiments, shown in FIGS. 7 through 10D, the cathode structure isrealized as a belt structure having ultrafine perforations in thesurface thereof to permit oxygen transport to the metal-fuel tape andthe ionically-conductive medium. The FCB systems classified into thesetwo groups will now be described in detail below.

First Illustrative Embodiment of the FCB System

In the first illustrative embodiment of the FCB system 10 shown in FIGS.2 through 2C, the cathode structure 4 is realized as a plasticcylindrical structure 11 having a hollow center 11A with fineperforations 12 in the surface thereof to permit oxygen transport to theinterface formed between the ionically-conductive medium and metal-fueltape 13 transported thereover. As shown, a cathode element 14 is mountedover the outer surface of the plastic hollow cylinder 11. The cathodeelement 14 is made from nickel mesh fabric 15 embedded within carbon andcatalytic material 16. Preferably, the metal-fuel tape 13 is transportedbetween a pair of supply and take-up reels as taught in Applicant'scopending application Ser. No. 09/074,337. Also, the metal-fuel tape canbe fabricated using any of the techniques taught in application Ser. No.09/074,337.

In the event that the cathode cylinder 11 is employed within aMetal-Fuel Tape Discharging Subsystem, then each of the subsystemscontained within the Metal-Fuel Tape Discharging Subsystem disclosed incopending application Ser. No. 09/074,337 can be incorporated into thesystem schematically depicted in FIG. 2. Thus, as taught in Applicant'scopending application Ser. Nos. 09/074,337 and 08/944,507, the interiorportion of the cathode cylindrical 11 shown in FIG. 2 can be equippedwith an oxygen-injection chamber (connected to an air pump or oxygensource), one or more pO₂ sensors, one or more temperature sensors,discharging head cooling equipment, and the like, so that systemcontroller 22 can control the pO₂ level within the cathode element 14,as well as maintain the temperature of the discharging head duringdischarging operations.

Similarly, in the event that the cathode cylinder 11 is employed withina Metal-Fuel Tape Recharging Subsystem, then each of the subsystemscontained within the Metal-Fuel Tape Recharging Subsystem disclosed incopending application Ser. No. 09/074,337 can be incorporated into thesystem schematically depicted in FIG. 2. Thus, as taught in Applicant'scopending application Ser. No. 09/074,337, the interior portion of thecathode cylindrical 11 shown in FIG. 2 can be equipped with anoxygen-evacuation chamber (connected to a vacuum pump or like device),one or more pO₂ sensors, one or more temperature sensors, recharginghead cooling equipment, and the like, so that system controller 22 cancontrol the pO₂ level within the cathode element 14, as well as maintainthe temperature of the recharging head during recharging operations.

As shown in FIG. 2, the cathode cylinder 11 is rotated about its axis ofrotation at an angular velocity controlled by a cathode drive unit 17.As shown, the cathode drive unit 17 has a drive shaft 18 with a gear 19that engages teeth formed on the edge of cylindrical structure 11. Themetal-fuel tape 13 is transported over the surface of the cylindricalcathode element 14 by a fuel-tape transporter 21 operable duringdischarging and recharging operations. The cathode drive unit 17 and thefuel-tape transporter 21 are controlled by a system controller 22 sothat the metal-fuel tape 13, the cathode structure 14 andionically-conductive medium are transported at substantially the samevelocity at the locus of points at which the ionically-conducing mediumcontacts the metal-fuel tape and the cathode structure. By controllingthe relative movement between the metal-fuel tape, ionically-conductivemedium and the cylindrical cathode structure, the system controller 22effectively minimizes the generation of frictional (e.g. shear) forcestherebetween and thus solves the problems associated with such forces.

In general, velocity control among the cathode structure,ionically-conductive medium and metal-fuel tape can be achieved invarious ways in the FCB system of FIG. 2. For example, one way would beto drive the cylindrical cathode structure 11 using a belt that is alsoused to transport the metal-fuel tape 13 (e.g. between supply andtake-up reels or hubs within a cassette type-device. Another way wouldbe to drive the cylindrical cathode structure 11 using a first set ofDC-controlled motors, while driving the supply and take-up hubs of thefuel cassette device using a second set of DC-controlled motors,synchronized with the first set of DC-controlled motors. Other ways ofachieving velocity control will become apparent to those skilled in theart having had the benefit of reading the present disclosure.

In general, it will be desired in most applications to mount a pluralityof pairs of “rotatable” cathode and anode contacting elements about thecylindrical cathode structure of the system of FIG. 2. Such anarrangement will enable maximum current collection from each rotatingcathode in the system, at the generated output voltage. For clarity ofexposition, however, only a single pair of cathode and anode contactingelements are shown mounted about the cathode cylinder in FIG. 2.

Specifically, as shown in FIG. 2, an electrically-conductive“cathode-contacting” element 23 is rotatably supported at each end ofthe cylindrical cathode structure 11 by a pair of brackets or likestructures so that the cathode-contacting element 23 is arranged inelectrical contact with the nickel mesh fabric 15 exposed on the outeredge portion 24 thereof and is permitted to rotate about the axis ofrotation of the cathode-contacting element as the cylindrical cathodestructure is rotated about the axis of rotation of the cylindricalcathode structure. Also as shown in FIG. 2, an electrically-conductive“anode-contacting” element 25 is rotatably supported by a pair ofbrackets 26 or like structures so that it is arranged closely adjacentthe cylindrical cathode structure, in electrical contact with theunderside surface of the metal-fuel tape 13, and permitted to rotateabout the axis of rotation of the anode-contacting element as themetal-fuel tape is transported over the rotating cathode structure withthe ionically-conductive medium disposed therebetween. As shown, therotatable cathode and anode contacting elements 23 and 25 areelectrically connected to electrical conductors (e.g. wiring) 27 and 28which are terminated at an output power controller 29. In turn, theelectrical load is connected to the output power controller 29 forreceiving a supply of electrical power from the FCB system.

As shown in FIG. 2, oxygen-rich air is permitted to flow through thehollow central bore 11A formed through the cylindrical cathode structure11 by passive diffusion, or by active forcing action created by a fan,turbine, or like structure. During tape discharging operations, theoxygen-rich air is permitted to flow through the perforations 12 formedin the cathode structure and reach the interface betweenionically-conductive medium (e.g. electrolyte) 30 and the metal-fueltape.

In the illustrative embodiment shown in FIG. 2, the ionically-conductivemedium 30 is realized as an ionically-conductive fluid or viscous gelapplied in the form of a thin film over the outer surface of the cathodecylinder 11. The ionically-conductive fluid/gel 30 can be applied to thesurface of the cathode element or metal-fuel tape in either a continuousor periodic manner to ensure that ionically-conductive medium issufficiently replenished during system operation and thus maintain anoptimum level of hydroxide ion concentration at the interface betweenthe ionically-conductive medium and metal-fuel tape. Notably, therequired thickness of the ionically-conductive film layer will vary fromapplication to application, but typically will depend on a number offactors including, for example, the electrical conductivity of theionically-conductive medium, the current flow expected to be produced bythe FCB system during discharging operations, the surface area of thecathode element, and the like.

Ionically-conductive fluid/gel 30 can be made using the followingformula. One mole of potassium hydroxide (KOH) and one mole of calciumchloride are dissolved in 100 grams of water. The function of KOH is toprovide a hydroxide ion source, whereas the function of calcium chlorideis as a hygroscopic agent. Thereafter, one-half a mole of polyethyleneoxide (PEO) is added to the mixture as an ion carrier. The mixture isthen blended for about 10 minutes. Thereafter, 0.1 mole of cellulosemethoxycarboxylic acid, a gellant, is added to the blended mixture. Thisformula results in the generation of an ionically-conductive gelsuitable for application to the surface of the cathode element 14 ormetal-fuel tape 13 of the FCB system.

Alternatively, ionically-conductive medium 30 can be realized as asolid-state ionically-conductive film applied to the outer surface ofthe cylindrical cathode element 14, or the inner surface of themetal-fuel tape. In this alternative embodiment of the presentinvention, the solid-state ionically-conductive film can be formed onthe cathode element or the metal-fuel tape using either of the followingformulas set forth below.

In accordance with the first formula, one mole of KOH, a hydroxidesource, and 0.1 mole of calcium chloride, a hygroscopic agent, aredissolved in the mixed solvents of 60 milliliters of water and 40milliliters of tetrahydrogen furan (THF). Thereafter, one mole of PEO isadded to the mixture as an ion carrier. Then, the resulting solution(e.g. mixture) is cast (i.e. coated) as a thick film onto the outersurface of the cathode element 14, or as a thick film onto the undersidesurface of the metal-fuel tape 13, whichever the case may be. Using theabove formulation, ionically-conductive film can be obtained with athickness in the range of about 0.2 mm to about 0.5 mm. As the mixedsolvents (i.e. water and THF) within the applied film coating areallowed to evaporate, an ionically-conductive solid state film is formedon the outer surface of the cathode element 14, or on the undersidesurface of the metal-fuel tape, whichever the case may be.

According to the second formula, one mole of KOH and 0.1 mole of calciumchloride are dissolved in the mixed solvents of 60 milliliters of waterand 40 milliliters of tetrahydrogen furan (THF). The function of KOH isas an ion source, whereas the function of the calcium chloride is as ahygroscopic agent. Thereafter, one mole of polyvinyl chloride (PVC) isadded to the solution in an amount sufficient to produce a gelatinoussubstance. The solution is then cast (coated) as a thick film onto theouter surface of the cathode element 14, or as a thick film onto on theunderside surface of the metal-fuel tape, whichever the case may be.Using the above formulation, ionically-conductive film can be obtainedwith a thickness in the range of about 0.2 mm to about 0.5 mm. As themixed solvents (i.e. water and THF) within the applied coating areallowed to evaporate, an ionically-conductive solid state film forms onthe outer surface of the cathode element 14, or on the underside surfacemetal-fuel tape, as the case may be.

When using the ionically-conductive media 30 as described hereinabove,it will necessary to provide a means for achieving “wetting” between (1)the ionically-conductive layer 30 and the metal-fuel tape 13, and (2)the ionically-conductive medium 30 and the movable cathode cylinder 11.One way of achieving wetting would be to continuously or periodicallyapply a coating of water (H₂O) and/or electrolyte make-up solution tothe surface of the metal-fuel tape 13 (and/or ionically-conductivemedium 30) during system operation to enable a sufficient level of ionictransport between the metal-fuel tape 13 and the ionically-conductivemedium 30 and also between the movable cathode cylinder 11 and theionically-conductive medium 30. Notably, the thickness of the watercoating applied to the metal-fuel tape (and/or the ionically-conductivemedium) will depend on the transport speed of the metal fuel tape, itswater absorption properties, etc. In the illustrative embodiment shownin FIG. 2, wetting of the metal-fuel tape 13 and/or ionically-conductivemedium 30 can be carried out using applicator 54 and dispensingmechanism 55. It is understood, however, that other methods of wettingthe metal-fuel tape 13 (13′, 13″) and/or ionically-conductive medium 30may be used with excellent results.

While the illustrative embodiments schematically depicted in FIG. 1 anddescribed hereinabove are shown for use in single-cathode/single-anodetype applications, it is understood that such system embodiments can bereadily modified to include a plurality of electrically-isolated cathodeelements formed about the plastic support cylinder 11 for use withmulti-track metal-fuel tape of the type taught in Applicant's copendingapplication Ser. Nos. 09/074,337 and 08/944,507, supra. The primaryadvantage of such system modifications is that it will be possible todeliver electrical power at various output voltage levels required byparticular electrical loads.

Second Illustrative Embodiment of the FCB System

In the second illustrative embodiment of the FCB system shown in FIGS. 2through 2C, is similar to the FCB system shown in FIG. 2 except that themetal-fuel tape employed in the FCB System of FIG. 3 has a solid-stateionically-conductive coating 31 applied to the underside surfacethereof, and not on the outer surface of the cathode structure as shownin FIG. 2.

In this alternative embodiment of the present invention, the metal-fueltape employed in the FCB System of FIG. 3 can be realized in a varietyof different ways. As shown in FIG. 3C1, a first type of metal-fuel tape13′ is formed by applying a ionically-conductive gel or gelatinous (i.e.solid-state) layer 31 to the surface of a thin layer of metal-fuel 32.As shown in FIG. 3C2, a second type of metal-fuel tape 13″ is formed byembodying an ionically-conductive medium 33 and metal-fuel particles 34within a substrate material 35. Techniques for fabricating such forms ofmetal-fuel are described in copending application Ser. No. 09/074,377.

Third Illustrative Embodiment of the FCB System

The third illustrative embodiment of the FCB system shown in FIGS. 4through 4C, is similar to the FCB system shown in FIG. 1 except that therotatable anode-contacting element 25 is arranged to establishelectrical contact with the outer surface of the metal-fuel tape 13.Consequently, the path of current flow through metal-fuel tape employedin the FCB system of FIG. 4 will be different from the path of currentflow through metal-fuel tape employed in the FCB system of FIG. 2. Allother respects, the FCB system of FIG. 4 is similar to the FCB system ofFIG. 2.

Fourth Illustrative Embodiment of the FCB System

The fourth illustrative embodiment of the FCB system shown in FIGS. 5through 5C2, is similar to the FCB system shown in FIG. 3 except thatthe rotatable anode-contacting element 25 is arranged to establishelectrical contact with the outer surface of the metal-fuel tape 13′,13″. Consequently, the path of current flow through metal-fuel tape 13′,13″ employed in the FCB system of FIG. 5 will be different from the pathof current flow through metal-fuel tape employed in the FCB system ofFIG. 3. All other respects, the FCB system of FIG. 5 and its embodimentsare similar to the FCB system of FIG. 3 and its embodiments.

Fifth Illustrative Embodiment of the FCB System

In FIG. 6, a fifth illustrative embodiment of the FCB system of thepresent invention is shown. In this illustrative embodiment, theionically-conductive medium is realized in the form of anionically-conductive belt structure running between a belt transportcylinder and a cathode cylinder of the general type shown in FIGS. 2, 3,4, and 5.

As shown in FIG. 6, the ionically-conductive belt 35 is rotatablysupported between cathode cylinder 11 as described hereinabove, and abelt transport cylinder 36 made of plastic or other electricallynon-conductive material. As shown, a supply of metal-fuel tape 13 istransported over the ionically-conducing belt 35, between a pair ofsupply and take-up reels as taught in Applicant's copending applicationSer. No. 09/074,337.

In the event that the cathode cylinder 11 is employed within aMetal-Fuel Tape Discharging Subsystem, then each of the subsystemscontained within the Metal-Fuel Tape Discharging Subsystem disclosed incopending application Ser. No. 09/074,337 can be incorporated into thesystem schematically depicted in FIG. 6. Thus, as taught in Applicant'scopending application Ser. Nos. 09/074,337 and 08/944,507, the interiorportion of the cathode cylindrical 11 shown in FIG. 6 can be equippedwith an oxygen-injection chamber (connected to an air pump or oxygensource), one or more pO₂ sensors, one or more temperature sensors,discharging head cooling equipment, and the like, so that systemcontroller 22 can control the pO₂ level within the cathode element 14,as well as maintain the temperature of the discharging head duringdischarging operations.

Similarly, in the event that the cathode cylinder 11 is employed withina Metal-Fuel Tape Recharging Subsystem, then each of the subsystemscontained within the Metal-Fuel Tape Recharging Subsystem disclosed incopending application Ser. No. 09/074,337 can be incorporated into thesystem schematically depicted in FIG. 6. Thus, as taught in Applicant'scopending application Ser. No. 09/074,337, the interior portion of thecathode cylindrical 11 shown in FIG. 6 can be equipped with anoxygen-evacuation chamber (connected to a vacuum pump or like device),one or more pO₂ sensors, one or more temperature sensors, recharginghead cooling equipment, and the like, so that system controller 22 cancontrol the pO₂ level within the cathode element 14, as well as maintainthe temperature of the recharging head during recharging operations.

As shown in FIG. 6, the cathode cylinder 11 is rotated at a controlledangular velocity by a cathode drive unit 38, while the belt transportcylinder 36 is rotated at a controlled angular velocity by an drive unit39. The metal-fuel tape 13 is transported over the surface of theionically-conductive belt 35 and cathode cylinder 11 by operation oftape transport mechanism 21 during discharging and rechargingoperations.

The drive units 38 and 39 and tape transporter 21 are controlled bysystem controller 22 so that the metal-fuel tape 13,ionically-conductive belt 35 and the cathode cylinder 11 are maintainedat substantially same velocity at the locus of points at which theionically-conductive belt 35 contacts the metal-fuel tape 13 and thecathode cylinder 11 during system operation. By controlling the relativemovement between the metal-fuel tape 13, ionically-conductive beltstructure 35 and cylindrical cathode structure 11, the system controller22 effectively minimizing the generation of frictional forcestherebetween and thus reduces the likelihood of damage caused to thecathode element 14 and metal-fuel tape 13.

In general, velocity control can be achieved in various ways in the FCBsystem of FIG. 6. For example, one way might be to drive the cathodecylindrical 11 and transport cylinder 36 using a belt-like structurethat is also used to transport the supply of metal-fuel tape (e.g.between supply and take-up reels or hubs within a cassette type-device).Another way would be to drive the cathode cylinder 11 and transportcylinder 36 with a pair of DC-controlled motors, while driving thesupply and take-up hubs of the fuel cassette device using a second pairof DC-controlled motors, synchronized with the first pair ofDC-controlled motors. Other ways of achieving velocity control willbecome apparent to those skilled in the art.

In general, it will be desired in most applications to mount a pluralityof pairs of “rotatable” cathode and anode contacting elements about thecathode cylinder of the system of FIG. 6. Such an arrangement willenable maximum current collection from each rotating cathode in thesystem, at the generated output voltage. For clarity of exposition,however, only a single pair of cathode and anode contacting elements areshown mounted about the cathode cylinder in FIG. 6.

As shown in FIG. 6, a electrically-conductive “cathode-contacting”element 23 is rotatably supported at each end of cathode cylinder 11 bya pair of brackets so that cathode-contacting element 23 is arranged inelectrical contact with the exposed nickel mesh fabric 20 on the edgeportions of the cathode cylinder 11 as the cathode cylinder is rotatedabout its axis of rotation. Also, an electrically-conductive“anode-contacting” element 25 is rotatably supported by brackets 26 thatare arranged closely adjacent the cathode cylinder, in electricalcontact with the outerside surface of the metal-fuel tape 13, as cathodecylinder is rotated about its axis of rotation. The cathode and anodecontacting elements 23 and 25 are electrically connected to electricalconductors (e.g. wiring) 28 and 28 which are terminated at an outputpower controller 29. An electrical load can be connected to the outputterminals of the output power controller 29 in order to receive a supplyof electrical power generated within the FCB system.

As shown in FIG. 6, oxygen-rich air is permitted to flow through thehollow central bore 11A formed through the cylindrical cathode structure11 by passive diffusion, or by active forcing action created by a fan,turbine, or like structure. During tape discharging operations, theoxygen-rich air is permitted to flow through the perforations 12 formedin the cathode structure 11 and reach the interface between themetal-fuel tape and the ionically-conductive belt structure 35.

In the illustrative embodiment shown in FIGS. 6 and 6A, theionically-conductive belt 35 can be realized as flexible belt havingionic-conduction characteristics. Such a belt can be made from anopen-cell polymer material having a porous structure and impregnatedwith an ionically-conductive material (e.g. KOH) capable of supportingionic transport between the cathode and anode structures of the FCBsystem. In general, there will be many ways of making theionically-conductive belt. For purposes of illustration, two formulasare described below.

In accordance with the first formula, one mole of KOH and 0.1 mole ofcalcium chloride are dissolved in the mixed solvents of 60 millilitersof water and 40 milliliters of tetrahydrogen furan (THF). The functionof KOH is as a hydroxide ion source, whereas calcium chloride is as ahygroscopic agent. Thereafter, one mole of PEO is added to the mixture.Then, the solution is cast (or coated) as a thick film onto substratemade of polyvinyl alcohol (PVA) type plastic material. This material hasbeen found to work well with PEO, although it is expect that othersubstrate materials having a surface tension higher than the filmmaterial should work as well with acceptable results. As the mixedsolvents evaporate from the applied coating, an ionically-conductivesolid state membrane (i.e. thick film) is formed on the PVA substrate.By peeling the solid state membrane off the PVA substrate, a solid-stateionically-conductive membrane or film is formed. Using the aboveformulation, it is possible to form ionically-conductive films having athickness in the range of about 0.2 to about 0.5 millimeters. Then, thesolid-state membrane can be cut into a shape required to form abelt-like structure transportable about two or more rotating cylinders.The ends of the shaped membrane can be joined by an adhesive,ultra-sonic welding, appropriate fasteners or the like to form asolid-state ionically-conductive belt structure 35 for use in the FCBsystems of the present invention.

In accordance with the second formula, one mole of KOH and 0.1 mole ofcalcium chloride are dissolved in the mixed solvents of 60 millimetersof water and 40 milliliters of tetrahydrogen furan (THF). The functionof KOH is as a hydroxide ion source, whereas calcium chloride is as ahygroscopic agent. Thereafter, one mole of polyvinyl chloride (PVC) isadded to the mixture. Then, the resulting solution is cast (or coated)as a thick film onto substrate made of polyvinyl alcohol (PVA) typeplastic material. This material has been found to work well with PVC,although it is expect that other substrate materials having a surfacetension higher than the film material should work as well withacceptable results. As the mixed solvents evaporate from the appliedcoating, an ionically-conductive solid state membrane (i.e. thick film)is formed on the PVA substrate. By peeling the solid state membrane offthe PVA substrate, a solid-state ionically-conductive membrane isformed. Using the above formulation, it is possible to formionically-conductive films having a thickness in the range of about 0.2to about 0.5 millimeters. Then, the solid-state film or membrane can becut into a shape required to form a belt-like structure transportableabout two or more rotating cylinders. The ends of the shaped membranecan be joined by an adhesive, ultra-sonic welding, appropriate fastenersor the like to form a solid-state ionically-conductive belt structure 35for use in the FCB systems of the present invention.

When using the ionically-conductive belt 35 described hereinabove, itwill necessary to provide a means for achieving “wetting” between (1)the ionically-conductive belt 35 and the metal-fuel tape 13 (13′, 13″),and (2) the ionically-conductive belt 35 and the rotatable cathodecylinder 11. One way of achieving wetting would be to continuously orperiodically apply a coating of water (H₂O) and/or electrolyte make-upsolution to the surface of the metal-fuel tape (and/orionically-conductive belt) during system operation to enable asufficient level of ionic transport between the metal-fuel tape and theionically-conductive belt and also between the movable cathode cylinderand the ionically-conductive belt. Notably, the thickness of the watercoating applied to the metal-fuel tape (and/or the ionically-conductivebelt) will depend on the transport speed of the metal fuel tape, itswater absorption properties, etc. In the illustrative embodiment shownin FIG. 6, wetting of the metal-fuel tape and/or ionically-conductivebelt can be carried out using applicator 54 and dispensing mechanism 55.It is understood, however, that other methods of wetting the metal-fueltape and/or ionically-conductive belt may be used with excellentresults.

While the illustrative embodiment shown in FIG. 6 is designed forsingle-cathode/single-anode type applications, it is understood thatthis system embodiment can be readily modified to include a plurality ofelectrically-isolated cathode elements formed about the cathode supportcylinder for use with multi-track type metal-fuel tape, as taught inApplicant's copending application Ser. No. 08/944,507, supra.

In this alternative embodiment of the present invention, the metal-fueltape for use in the FCB System of FIG. 6 can be realized in a variety ofdifferent ways. As shown in FIG. 6B, a first type of metal-fuel tape 13is formed as a thin layer of metal-fuel material (e.g. zinc). A secondtype of metal-fuel tape 13′ is formed by depositing a metallic powder(e.g. zinc powder) and binder (e.g. PVC) 31 on a polyester substrate 32.As shown in FIG. 6D, a third type of metal-fuel tape 13″ is formed byimpregnating metallic powder 33 (e.g. zinc powder) within a substratematerial 34 such as PVC. Techniques for fabricating such forms ofmetal-fuel are described in copending application Ser. No. 09/074,337.

Sixth Illustrative Embodiment of the FCB System

In FIG. 7, a sixth illustrative embodiment of the FCB system of thepresent invention is shown. In this illustrative embodiment, the movingcathode structure is realized as a cathode belt structure 40 runningbetween a pair of cylindrical rollers 41 and 42, over which a supply ofmetal-fuel tape 13 (13′, 13″) is transported.

As shown in FIG. 7, the cathode belt structure 40 is rotatably supportedbetween cylindrical rollers 41 and 42 driven by drive units 38 and 39,while a supply of metal-fuel tape 13 (13′, 13″) is transported over thecathode belt structure 40 and between a pair of supply and take-up reelsas taught in Applicant's copending application Ser. No. 09/074,337. Thedrive units 38 and 39 and metal-fuel tape transporter 21 are controlledby system controller 22 so that the velocity of both the metal-fuel tape13 (13′,13″) and the cathode belt structure 40 are maintained atsubstantially the same velocity at the locus of points which theionically-conducing medium contacts the metal-fuel tape and the cathodestructure during system operation. By controlling the relative movementbetween the metal-fuel tape and cathode belt structure betweencylindrical rollers 41 and 42, the system controller 22 effectivelyminimizes the generation of frictional forces therebetween and thusreduces wearing and tearing of the metal-fuel tape 13.

The cathode belt 40 has ultrafine perforations in the surface thereof topermit oxygen transport to the anodic metal-fuel tape 13 (13′,13″)passing thereover. A preferred method of making the flexible cathodestructure is to blend black Carbon powder (60%/weight), with a bindermaterial such as Teflon emulsion(T-30 from Dupont) (20%/weight), andcatalyst material such as magnesium dioxide MnO₂ (20%/weight) within 100milliliters of water (solvent) and surfactant (e.g Triton X-10 fromUnion Carbide) 2.0%/weight in order to make a slurry. Then the slurry iscast or coated onto the nickel sponge (or mesh fabric material). Theslurry-coated nickel mesh fabric is then air dried for about 10 hours.Thereafter, dried article is compressed at 200 [pounds/cm²] in to formflexible cathodic material having a desired porosity (e.g. 30-70%) andabout 0.5-0.6 millimeters. It is understood, however, that the thicknessand porosity of the cathode material may vary from application toapplication. The cathode material is then sintered at about 280 degreeC. for about 2 hours to remove the solvent (i.e. water) and provide aflexible sheet of cathodic material which can then be cut into thedesired dimensions to form a cathode belt structure for the FCB systemunder design. The ends of belt structure can be joined by soldering,fasteners, or the like to form a virtually seamless cathode surfaceabout closed belt structure. The nickel mesh material can be exposed atthe ends of the cathode belt structure 40 to allow cathode contactingelements 48 to establish electrical contact therewith during dischargingand recharging operations.

When using the ionically-conductive media 53 described hereinabove, itwill necessary to provide a means for achieving “wetting” between (1)the ionically-conductive medium 53 and the metal-fuel tape 13 (13′,13″), and (2) the ionically-conductive medium 53 and the movable cathodebelt 40. One way of achieving wetting would be to continuously orperiodically apply a coating of water (H₂O) to the surface of themetal-fuel tape (and/or ionically-conductive medium 53) during systemoperation to enable a sufficient level of ionic transport between themetal-fuel tape and the ionically-conductive medium 53 and also betweenthe movable cathode belt 40 and the ionically-conductive medium 53.Notably, the thickness of the water coating applied to the metal-fueltape 13 (and/or the ionically-conductive medium 53) will depend on thetransport speed of the metal fuel tape 13, its water absorptionproperties, etc. In the illustrative embodiment shown in FIG. 7, wettingof the metal-fuel tape and/or ionically-conductive medium 53 can becarried out using applicator 54 and dispensing mechanism 55. It isunderstood, however, that other methods of wetting the metal-fuel tapeand/or ionically-conductive medium 53 may be used with excellentresults.

In general, velocity control can be achieved in various ways in the FCBsystem of FIG. 7. For example, one way might be to drive transportcylinders 41 and 42 with a belt structure that is also used to transportthe metal-fuel tape 13 (e.g. between supply and take-up reels or hubswithin a cassette type-device). Another way might be to drive transportcylinders 41 and 42 with a first pair of DC-controlled motors, whiledriving the supply and take-up hubs of the metal-fuel cassette deviceusing a pair of DC-controlled motors, synchronized with the first andsecond DC speed-controlled motors. Other ways of achieving velocitycontrol will become apparent to those skilled in the art.

In general, it will be desired in most applications to mount a pluralityof pairs of “rotatable” cathode and anode contacting elements about thecathode belt structure of the system of FIG. 7. Such an arrangement willenable maximum current collection from each cathode belt structure inthe system, at the generated output voltage. For clarity of exposition,however, only a single pair of cathode and anode contacting elements.are shown mounted along the cathode belt structure in FIG. 7.

As shown in FIG. 7, the electrically-conductive “cathode-contacting”element 48 is rotatably supported by a pair of brackets 49 so that it isarranged in electrical contact with the exposed nickel mesh fabric 45 onthe edge portions of the cathode belt structure 40 as it is transportedbetween transport cylinders 41 and 42. Also, an electrically-conductive“anode-contacting” element 50 is rotatably supported by brackets 49 ,above the metal-fuel tape 13 (13′, 13″) and opposite the cathodecontacting element 48, so that anode-contacting element establisheselectrical contact with the outerside surface of the metal-fuel tape, asshown in FIG. 7. The cathode and anode contacting elements 48 and 50 areelectrically connected to electrical conductors (e.g. wiring) which areterminated at an output power controller 29. An electrical load can beconnected to the output terminals of the output power controller 29 inorder to receive a supply of electrical power generated within the FCBsystem.

In the event that the cathode belt 40 is employed within a Metal-FuelTape Discharging Subsystem, then each of the subsystems contained withinthe Metal-Fuel Tape Discharging Subsystem disclosed in copendingapplication Ser. No. 09/074,337 can be incorporated into the systemschematically depicted in FIG. 7. Thus, as taught in Applicant'scopending application Ser. Nos. 09/074,337 and 08/944,507, a portion ofthe cathode belt structure 40 shown in FIG. 7, along which electricalcurrent is generated, can be enclosed by an oxygen-injection chamber(connected to an air pump or oxygen source), and having one or more pO₂sensors, one or more temperature sensors, discharging head coolingequipment, and the like, so that system controller 22 can control thepO₂ level within this section of the moving cathode belt structure 40,as well as maintain the temperature of the discharging head therealongduring discharging operations.

Similarly, in the event that the cathode belt structure 40 is employedwithin a Metal-Fuel Tape Recharging Subsystem, then each of thesubsystems contained within the Metal-Fuel Tape Recharging Subsystemdisclosed in copending application Ser. No. 09/074,337 can beincorporated into the system schematically depicted in FIG. 7. Thus, astaught in Applicant's copending application Ser. Nos. 09/074,337 and08/944,507, a portion of the cathode belt structure 40 shown in FIG. 7,along which electrical current is generated, can be enclosed by anoxygen-evacuation chamber (connected to a vacuum pump or like device),and having one or more pO₂ sensors, one or more temperature sensors,recharging head cooling equipment, and the like, so that systemcontroller 22 can control the pO₂ level within this section of themoving cathode belt structure 40, as well as maintain the temperature ofthe recharging head therealong during recharging operations.

As shown in FIG. 7, during tape discharging operations, oxygen-rich airis permitted or forced to flow through the fine perforations 21 formedin the cathode belt structure 40 and reach the interface between themetal-fuel tape 13′, 13″, and the ionically-conductive medium (e.g.electrolyte gel) 53. During tape recharging operations, oxygen liberatedfrom the interface between the metal-fuel tape and theionically-conductive medium (e.g. electrolyte gel) is permitted orforced to flow through the fine perforations 21 formed in the cathodebelt structure 40, to the ambient environment.

In the illustrative embodiment shown in FIGS. 7 and 7A, the outersurface of cathode belt structure 40 (i.e facing the metal-fuel tapetransported thereover) is coated with a solid-state ionically-conductivefilm 53 capable of supporting ionic transport between the cathode beltstructure 40 and the metal-fuel tape 13 (13′,13″) transported throughthe FCB system. Alternatively, the under surface of metal-fuel tapefacing the cathode belt structure 40 can be coated with a solid-stateionically-conductive film 53 capable of supporting ionic transportbetween the cathode belt structure 40 and the metal-fuel material alongthe transported metal-fuel tape 13 (13′, 13″). This approach wouldenable to the use of a simpler cathode belt structure within the FCBsystem of this illustrative embodiment.

Another alternative method of supporting ionic transport between thecathode belt structure 40 and the metal-fuel tape 13 (13′, 13″) is toapply a film of an ionically-conductive gel (or liquid) 53 onto theunderside surface 13A of the metal-fuel tape as it is being transportedover the cathode belt structure 40. This can be achieved usingapplicator 54, disposed beneath the metal-fuel tape 13 (13′, 13″), andfed by dispenser 55 governed by system controller 22. During operation,a thin layer of ionically-conductive gel 53 is dispensed from applicator54 over the surface of the metal-fuel tape contacting the cathode belt40. Notably, the required thickness of the ionically-conductive filmlayer will vary from application to application, but typically willdepend on a number of factors including, for example, the electricalconductivity of the ionically-conductive medium, the current flowexpected to be produced by the FCB system during discharging operations,the surface area of the cathode element, and the like.

While the illustrative embodiment shown in FIG. 7 is designed forsingle-cathode/single-anode type applications, it is understood thatthis system embodiment can be readily modified to include a plurality ofelectrically-isolated cathode elements (tracks) formed along theflexible cathode belt structures for use with multi-track metal-fueltape, as taught in Applicant's copending application Ser. No.08/944,507, supra.

In alternative embodiments of the present invention, the metal-fuel tapefor use with the FCB system of FIG. 7 can be realized in a variety ofdifferent ways. As shown in FIG. 7B, the first type of metal-fuel tape13 is formed as a thin layer of metal-fuel material (e.g. zinc). Thesecond type of metal-fuel tape 13′ shown in FIG. 7C is formed bydepositing a metallic powder (e.g. zinc powder) and binder (e.g.polyethylene) 31 on a polyester substrate 32. As shown in FIG. 7D, athird type of metal-fuel tape 13″ is formed by impregnating metallicpowder 33 (e.g. zinc powder) within a substrate material 34 such aspolyvinyl chloride PVC. Techniques for fabricating such forms ofmetal-fuel are described in copending application Ser. Nos. 08/944,507and 09/074,337.

During system operation, the cathode belt structure 40 is transported ata controlled velocity between the transport cylinders 41 and 42.Therewhile, the supply of metal-fuel tape 13 (13′, 13″) is transportedover the surface of the cathode belt structure 40 at substantially thesame velocity that the ionically-conducing medium contacts themetal-fuel tape and the cathode belt structure 40, and enableselectrical power generation without slippage or causing damage to thecathode belt structure and metal-fuel tape.

Seventh Illustrative Embodiment of the FCB System

In FIG. 8, a seventh illustrative embodiment of the FCB system is shownwhich is similar to the FCB system shown in FIG. 7. The primarydifference between these two systems is that in FIG. 8, thecathode-contacting element 48 is placed close to the transport cylinder41 so that it contacts the outer surface of the conductivebelt-structure 40, whereas the anode-contacting element 50 is placedclosely to the cathode-contacting electrode 48 and establishes contactwith the underside of the supply of metal-fuel tape 13 (13′, 13″) beingtransported over the cathode belt structure 40. Consequently, the pathof electrical current flow through metal-fuel tape 13 (13′, 13″)employed in the FCB system of FIG. 8 will be different from the path ofcurrent flow through metal-fuel tape 13 (13′, 13″) employed in the FCBsystem of FIG. 7. All other respects, the FCB system of FIG. 8 issimilar to the FCB system of FIG. 7.

Eighth Illustrative Embodiment of the FCB System

In FIG. 9, an eighth illustrative embodiment of the FCB system is shownwhich is similar to the FCB system shown in FIG. 7. The primarydifference between these two systems is that in FIG. 9, theionically-conductive medium is realized as an ionically-conductive layerformed on the underside of the supply of the metal-fuel tape 13 (13′,13″). As shown in FIG. 9B, the first type of metal-fuel tape 58 isformed as a thin layer of metal-fuel material (e.g. zinc) 59, onto whichan ionically-conductive layer 60 is laminated. A second type ofmetal-fuel tape 58′ shown in FIG. 9C is formed by depositing a metallicpowder (e.g. zinc powder) and binder (e.g. PVC) 61 on a polyestersubstrate 62 , onto which an ionically-conductive layer 60′ islaminated. As shown in FIG. 9D, a third type of metal-fuel tape 58″ isformed by impregnating metallic powder 63 ( e.g. zinc powder) within asubstrate material 64 such as PVC, onto which an ionically-conductivelayer 60 is laminated. Techniques for fabricating such forms ofmetal-fuel are described in copending application Ser. Nos. 08/9444,507and 08/074,337. All other respects, the FCB system of FIG. 9 is similarto the FCB system of FIG. 7.

Ninth Illustrative Embodiment of the FCB System

FIG. 10 shows a ninth illustrative embodiment of the FCB system of thepresent invention. In this illustrative embodiment, the cathodestructure is realized as a belt structure 40 transported between a firstpair of cylindrical rollers 41 and 42 driven by drive units 37 and 38respectively, in a manner similar to the way shown in FIGS. 7 through9D. The ionically-conductive medium is realized as anionically-conductive belt 35 transported between transport cylinder 66and transport cylinder 42 driven by drive units 62 and 38, respectively,in a manner similar as shown in FIG. 6. A supply of metal-fuel tape 13(13′, 13″) is transported over the ionically-conductive belt structure35 between a pair of supply and take-up reels as taught in Applicant'scopending application Ser. Nos. 08/944,507 and 09/074,337. The driveunits 38, 39, and 62 as well as tape drive units 21 are controlled by asystem controller 22 so that the velocity of both the metal-fuel tape13, ionically-conductive belt structure 35 and the cathode beltstructure 40 are maintained at substantially the same velocity at thelocus of points at which the ionically-conducing belt structure 35contacts the metal-fuel tape and the cathode belt structure 40 duringsystem operation. By controlling the relative movement between themetal-fuel tape, ionically-conductive belt structure 35 and cathode beltstructure 40, the system controller 22 minimizes the generation offrictional forces therebetween and thus the problems associatedtherewith.

In general, velocity control can be achieved in various ways in the FCBsystem of FIG. 10. For example, one way might be to drive the transportcylinders 41, 42 and 66 using a belt structure that is also used totransport the metal-fuel tape 13 (e.g. between supply and take-up reelsor hubs within a cassette type-device). Another way might be to drivetransport cylinders 41, 42 and 66 with a first set of DC-controlledmotors, while driving the supply and take-up hubs of the metal-fuelcassette device using a different set of DC-controlled motors,synchronized with the first set of DC-controlled motors. Other ways ofachieving velocity control among the movable components of the FCBsystem will become apparent to those skilled in the art.

In general, it will be desired in most applications to mount a pluralityof pairs of “rotatable” cathode and anode contacting elements about thecathode belt structure of the system of FIG. 10. Such an arrangementwill enable maximum current collection from each moving cathode beltstructure in the system, at the generated output voltage. For clarity ofexposition, however, only a single pair of cathode and anode contactingelements are shown in FIG. 10.

As shown in FIG. 10, an electrically-conductive “cathode-contacting”element 48 is rotatably supported by a pair of brackets 69 so that it isarranged in electrical contact with the exposed nickel mesh fabric onthe outer edge portions of the cathode belt structure 40 as the cathodebelt structure is transported about transport cylinder 41. Also, anelectrically-conductive “anode-contacting” element 50 is rotatablysupported by a pair of brackets 70 disposed above the metal-fuel tapeand opposite the cathode contacting element 48, so that theanode-contacting element establishes electrical contact with theouterside surface of the metal-fuel tape 13 (13′, 13″), as shown in FIG.10. The cathode and anode contacting elements 48 and 50 are connected toelectrical conductors (e.g. wiring) which are terminated at an outputpower controller 29. An electrical load can be connected to the outputterminal of the output power controller 29 in order to receive a supplyof electrical power generated within the FCB system.

When using the ionically-conductive belt 35 described hereinabove, itwill necessary to provide a means for achieving “wetting” between (1)the ionically-conductive belt and the metal-fuel tape 13 (13″, 13″), and(2) the ionically-conductive belt 35 and the movable cathode belt 40.One way of achieving wetting would be to continuously or periodicallyapply a coating of water (H₂O) and/or electrolyte make-up solution tothe surface of the metal-fuel tape (and/or ionically-conductive belt)during system operation to enable a sufficient level of ionic transportbetween the metal-fuel tape and the ionically-conductive belt and alsobetween the movable cathode belt and the ionically-conductive medium.Notably, the thickness of the water coating applied to the metal-fueltape (and/or the ionically-conductive belt 35) will depend on thetransport speed of the metal fuel tape, its water absorption properties,etc. In the illustrative embodiment shown in FIG. 10, wetting of themetal-fuel tape and/or ionically-conductive belt 35 can be carried outusing applicator 54 and dispensing mechanism 55 controlled by the systemcontroller 22. It is understood, however, that other methods of wettingthe metal-fuel tape 13 (13′, 13″) and/or ionically-conductive belt 35may be used with excellent results.

In the event that the cathode belt 40 is employed within a Metal-FuelTape Discharging Subsystem, then each of the subsystems contained withinthe Metal-Fuel Tape Discharging Subsystem disclosed in copendingapplication Ser. No. 09/074,337 can be incorporated into the systemschematically depicted in FIG. 10. Thus, as taught in Applicant'scopending application Ser. Nos. 09/074,337 and 08/944,507, a portion ofthe cathode belt structure 40 shown in FIG. 10, along which electricalcurrent is generated, can be enclosed by an oxygen-injection chamber(connected to an air pump or oxygen source), and having one or more pO₂sensors, one or more temperature sensors, discharging head coolingequipment, and the like, so that system controller 22 can control thepO₂ level within this section of the moving cathode belt structure 40,as well as maintain the temperature of the discharging head therealongduring discharging operations.

Similarly, in the event that the cathode belt structure 40 is employedwithin a Metal-Fuel Tape Recharging Subsystem, then each of thesubsystems contained within the Metal-Fuel Tape Recharging Subsystemdisclosed in copending application Ser. No. 09/074,337 can beincorporated into the system schematically depicted in FIG. 10. Thus, astaught in Applicant's copending application Ser. Nos. 09/074,337 and08/944,507, a portion of the cathode belt structure 40 shown in FIG. 10,along which electrical current is generated, can be enclosed by anoxygen-evacuation chamber (connected to a vacuum pump or like device),and having one or more pO₂ sensors, one or more temperature sensors,recharging head cooling equipment, and the like, so that systemcontroller 22 can control the pO₂ level within this section of themoving cathode belt structure 40, as well as maintain the temperature ofthe recharging head therealong during recharging operations.

As shown in FIG. 10, during tape discharging operations, oxygen-rich airis permitted or forced to flow through the fine perforations 21 formedin the cathode belt structure 40 and reach the interface between themetal-fuel tape and the ionically-conductive belt 35. During taperecharging operations, oxygen liberated from the interface between themetal-fuel tape and the ionically-conductive belt 35 is permitted orforced to flow through the fine perforations 21 formed in the cathodebelt structure 40, to the ambient environment.

While the illustrative embodiment shown in FIG. 10 is designed forsingle-cathode/single-anode type applications, it is understood thatthis system embodiment can be readily modified to include a plurality ofelectrically-isolated cathode elements formed along the cathode beltstructure 40 for use with multi-track metal-fuel tape, as taught inApplicant's copending application Ser. Nos. 08/944,507 and 09/074,337,supra.

In alternative embodiments of the present invention, the metal-fuel tapeused in the FCB System of FIG. 10 can be realized in a variety ofdifferent ways. As shown in FIG. 10C, the first type of metal-fuel tape13 is formed as a thin layer of metal-fuel material (e.g. zinc). Thesecond type of metal-fuel tape 13′ shown in FIG. 10D is formed bydepositing a metallic (e.g. zinc) powder and binder (e.g. PVC) 31 on apolyester substrate 32. As shown in FIG. 10E, the third type ofmetal-fuel tape 13″ is formed by impregnating metallic powder ( e.g.zinc powder) 33 within a substrate material 34 such as PVC. Techniquesfor fabricating such forms of metal-fuel are described in copendingApplication Ser. Nos. 08/944,507 and 09/074,337.

During discharging operations, the cathode belt structure 40 istransported at a controlled velocity between transport cylinders 41 and42, while the ionically-conductive belt structure 35 is transported at acontrolled velocity between transport cylinders 41 and 42. Therewhile, acontinuous supply of metal-fuel tape 13 (13′, 13″) is transported overthe surface of the cathode belt structure 40 at substantially the samevelocity at the locus of points at which the ionically-conducing beltstructure 35 contacts the metal-fuel tape and the cathode belt structure40 without slippage.

Alternative Embodiments of The FCB System of The Present Invention

Having described the illustrative embodiments of the present invention,several modifications thereto readily come to mind which would beadvantageous in the commercial practice of the present invention.

In order to eliminate the need to separately drive and actively controlthe velocity of the metal-fuel tape, movable cathode structure andionically-conductive medium in the system hereof using complexmechanisms, the present invention also contemplates creating a conditionof “hydrostatic drag” (i.e. hydrostatic attraction) between themetal-fuel tape and the ionically-conductive medium (e.g. belt orapplied gel/solid-state film), and the ionically-conductive medium (e.g.belt or applied gel/solid-state film and the cathode structure (e.g.cylinder or belt). This condition will enable a more efficienttransportation of the metal-fuel tape, ionically-conductive medium andmovable cathode structure through the FCB system when transporting onlyone of these three movable system components (e.g. metal-fuel tape,ionically-conductive medium, or movable cathode structure) using amechanically (e.g. spring-wound), electrically, or pneumatically drivenmotor. This reduces the complexity of the system as well as the cost ofmanufacture thereof. Also, it enables the metal-fuel tape,ionically-conductive medium, and cathode structures to be moved withinthe system without generating significant frictional (e.g. shear)forces, and thus transporting these moving components usingtorque-control (or current control) techniques regulated by the ouputpower requirements set by electrical loading conditions at any instantin time.

Hydrostatic drag can be created between these system components bymaintaining a sufficient level of surface tension between theionically-conductive medium and the metal-fuel tape, and theionically-conductive medium and the movable cathode structure duringsystem operation.

When using the ionically-conductive media disclosed hereinabove,sufficient surface tension can be created between the three primarymoving components of the FCB system by continuously or periodicallyapplying an even coating of water (H₂O) and/or electrolyte make-upsolution to the surface of the metal-fuel tape (and/orionically-conductive medium) so that, during system, operation “wetting”occurs between (1) the ionically-conductive medium and the metal-fueltape, and (2) the ionically-conductive medium and the movable cathodestructure. Notably, the thickness of the water coating and/orelectrolyte make-up solution applied to the metal-fuel tape (and/or theionically-conductive medium) will depend on the transport speed of themetal fuel tape, its water absorption properties, etc. In each of theillustrative embodiments disclosed herein, wetting of the metal-fueltape and/or ionically-conductive medium can be carried out usingapplicator 54 and dispensing mechanism 55 shown in the figure drawingshereof. It is understood, however, that other methods of wetting themetal-fuel tape and/or ionically-conductive medium may be used withexcellent results.

For example, in the illustrative embodiment shown in FIG. 4, periodic orcontinuously wetting of the metal-fuel tape 8 and theionically-conductive coating 30 on the cathode cylinder 11 can createsufficient surface tension therebetween, and thus sufficient hydrostaticdrag, to enable the cathode cylinder 11 to passively move (i.e. rotate)at the same velocity as the metal-fuel tape in contact therewith whileonly the metal-fuel tape is being actively driven by its tape transportmechanism 21. In this alternative embodiment of the present invention,the use of cathode cylinder drive unit 17 and velocity equalization bysystem controller 22 can be eliminated while still achieving theprinciples of the present invention. This modification would reduces thecomplexity of the system as well as its cost of manufacture andmaintenance.

In the illustrative embodiment shown in FIG. 5, periodic or continuouslywetting of the ionically-conductive coating 30 on the metal-fuel tape 8and the cathode cylinder 11 can create sufficient surface tensiontherebetween, and thus sufficient hydrostatic drag, to enable thecathode cylinder 11 to passively move at the same velocity as themetal-fuel tape in contact therewith while only the metal-fuel tape isbeing actively driven by its tape transport mechanism 21. In thisalternative embodiment of the present invention, the use of cathodecylinder drive unit 17 and velocity equalization by system controller 22can be eliminated while still achieving the principles of the presentinvention. This modification would reduces the complexity of the systemas well as its cost of manufacture and maintenance.

In the illustrative embodiment shown in FIG. 6, periodic or continuouslywetting of the metal-fuel tape 13 (13′, 13″), ionically-conductive belt35, and cathode cylinder 11 can create sufficient surface tensiontherebetween, and thus sufficient hydrostatic drag, to enable thecathode cylinder 11, belt transport cylinder 36 and ionically-conductivebelt 35 to passively rotate at the same velocity as the metal-fuel tape13 in contact therewith while only the metal-fuel tape 13 is beingactively driven by its tape transport mechanism 21. In this alternativeembodiment of the present invention, the use of cylinder drive units 38and 39 and velocity equalization by system controller 22 can beeliminated while still achieving the principles of the presentinvention. Alternatively, it may be possible in some instances toactively drive the ionically-conductive belt 35 and allow the cathodecylinder 11, and metal fuel tape 13 to passively move at the samevelocity as the ionically-conductive belt 35 in contact therewith. Ineither case, such modifications will reduce the complexity of the systemas well as its cost of manufacture and maintenance.

In the illustrative embodiment shown in FIG. 7, periodic or continuouslywetting of the metal-fuel tape 13 (13′, 13″) and theionically-conductive medium 53 on and cathode belt 40 can createsufficient surface tension therebetween, and thus sufficient hydrostaticdrag, to enable the cathode belt 40, belt transport cylinder 41 andionically-conductive belt 42 to passively rotate at the same velocity asthe metal-fuel tape 13 in contact therewith while only the metal-fueltape 13 is being actively driven by its tape transport mechanism 21. Inthis alternative embodiment of the present invention, the use ofcylinder drive units 38 and 39 and velocity equalization by systemcontroller 22 can be eliminated while still achieving the principles ofthe present invention. Alternatively, it may be possible in someinstances to actively drive the cathode belt 40 and allow the metal fueltape 13 to passively move at the same velocity as theionically-conductive medium 53 in contact therewith. In either case,such modifications will reduce the complexity of the system as well asits cost of manufacture and maintenance.

In the illustrative embodiment shown in FIG. 8, periodic or continuouslywetting of the metal-fuel tape 13 (13′, 13″) and theionically-conductive medium 53 on and cathode belt 40 can createsufficient surface tension therebetween, and thus sufficient hydrostaticdrag, to enable the cathode belt 40, belt transport cylinder 41 andionically-conductive belt 42 to passively rotate at the same velocity asthe metal-fuel tape 13 in contact therewith while only the metal-fueltape 13 is being actively driven by its tape transport mechanism 21. Inthis alternative embodiment of the present invention, the use ofcylinder drive units 38 and 39 and velocity equalization by systemcontroller 22 can be eliminated while still achieving the principles ofthe present invention. Alternatively, it may be possible in someinstances to actively drive the cathode belt 40 and allow the metal fueltape 13 to passively move at the same velocity as theionically-conductive medium 53 in contact with the cathode belt andmetal-fuel tape. In either case, such modifications will reduce thecomplexity of the system as well as its cost of manufacture andmaintenance.

In the illustrative embodiment shown in FIG. 9, periodic or continuouslywetting of the cathode belt 40 and the ionically-conductive medium 53 onthe metal-fuel tape 13 (13′, 13″) can create sufficient surface tensiontherebetween, and thus sufficient hydrostatic drag, to enable thecathode belt 40, belt transport cylinder 41 and ionically-conductivebelt 42 to passively rotate at the same velocity as the metal-fuel tape13 in contact therewith while only the metal-fuel tape 13 is beingactively driven by its tape transport mechanism 21. In this alternativeembodiment of the present invention, the use of cylinder drive units 38and 39 and velocity equalization by system controller 22 can beeliminated while still achieving the principles of the presentinvention. Alternatively, it may be possible in some instances toactively drive the cathode belt 40 and allow the ionically-conductivemedium 53 (and metal fuel tape 13) to passively move at the samevelocity as the cathode belt 40 in contact with the ionically-conductivemedium 53. In either case, such modifications will reduce the complexityof the system as well as its cost of manufacture and maintenance.

In the illustrative embodiment shown in FIG. 10, periodic orcontinuously wetting of the metal-fuel tape 13 (13′, 13″) and theionically-conductive belt 35 on and cathode belt 40 can createsufficient surface tension therebetween, and thus sufficient hydrostaticdrag, to enable the cathode belt 40, ionically-conductive belt 35 andbelt transport cylinders 41, 42 and 66 to passively move at the samevelocity as the metal-fuel tape 13 in contact with ionically-conductivebelt 35 while only the metal-fuel tape 13 is being actively driven byits tape transport mechanism 21. In this alternative embodiment of thepresent invention, the use of cylinder drive units 38, 39 and 67 andvelocity equalization by system controller 22 can be eliminated whilestill achieving the principles of the present invention. Alternatively,it may be possible in some instances to actively drive the cathode belt40 (or ionically-conductive belt 35) and allow the metal fuel tape 13 topassively move at the same velocity as the ionically-conductive belt 35in contact therewith. In either case, such modifications will reduce thecomplexity of the system as well as its cost of manufacture andmaintenance.

In addition, a plurality of cathode cylinders (or cathode belts) of thegeneral type disclosed hereinabove can be rotatably mounted within anarray-like support structure as disclosed in Applicant's copendingapplication Ser. No. 09/110,761 entitled “Metal-Air Fuel Cell BatterySystem Employing a Plurality of Moving Cathode Structures for ImprovedVolumetric Power Density” filed on the same date herewith, andincorporated herein by reference in its entirety. The cathode supporttube of each such cylindrical cathode structure can be driven by asupply of metal-fuel tape transported over the surfaces thereof inaccordance with a predefined tape pathway. Transport of the metal-fueltape can be carried out using a tape transport mechanism similar to thatdisclosed in Applicant's copending application Ser. No. 09/074,337. Theionically-conductive medium can be realized as a solid-state film orlayer applied to either the outer surface of each cylindrical cathodestructure or the surface of the metal-fuel tape, as described in thevarious illustrative embodiments described herein. Alternatively, theionically-conductive medium can be realized as an ionically-conductivebelt structure that is transported through the cylindrical cathodearray, while disposed between the metal-fuel tape and the surface of thecathode cylinders. Using this system design, it is possible to generatevery high electrical power output from physical structures occupyingrelatively small volumes of space, thereby providing numerous advantagesover prior art FCB systems.

The above-described FCB systems of the present invention can be used topower various types of electrical circuits, systems and devices,including, but not limited to, power tools, consumer appliances,stand-alone portable generators, vehicular systems, and the like.

Having described in detail the various aspects of the present inventiondescribed above, it is understood that modifications to the illustrativeembodiments will readily occur to persons with ordinary skill in the arthaving had the benefit of the present disclosure. All such modificationsand variations are deemed to be within the scope and spirit of thepresent invention as defined by the accompanying claims to invention.

What is claimed is:
 1. A cathode belt structure for use in a metal-airfuel cell battery system, comprising: a flexible belt portiontransportable between two or more support rollers during operation ofsaid metal-air fuel cell battery system, said flexible belt portionfurther having an outer surface and a constitution allowing oxygen toflow through said outer surface along said flexible belt portion towardsan ionically-conductive medium in contact with said outer surface duringoperation of said metal-air fuel cell battery system; a catalytic mediumembodied within said flexible belt portion, for supporting a catalyticreaction at the interface formed between said ionically-conductivemedium and said outer surface as metal-fuel material is transported oversaid ionically-conductive medium in contact with said outer surfaceduring operation of said metal-air fuel cell battery system; and acurrent-collecting medium embodied within said flexible belt portion,for collecting electrical current produced as metal-fuel material istransported over said ionically-conductive medium in contact with saidouter surface during operation of said metal-air fuel cell batterysystem.
 2. The cathode belt structure of claim 1, wherein saidionically-conductive medium comprises a solid-state film havingionically-conductive properties, applied to said outer surface of saidflexible belt portion.
 3. The cathode belt structure of claim 1, whereinsaid ionically-conductive medium comprises a solid-state film that isgelatinous.
 4. The cathode belt structure of claim 1, wherein saidcurrent collecting medium comprises a nickel mesh fabric or spongematerial embedded with said catalytic material, carbon and bindermaterial.
 5. The cathode belt structure of claim 1, comprising aFluoroethylene polymer.
 6. The cathode belt structure of claim 1,wherein porosity of said flexible belt portion is the range from about30 to about 70%, and thickness of said flexible belt portion is in therange from about 0.2 to about 0.6 millimeters.
 7. A method offabricating a cathode belt structure for use in a metal-air fuel cellbattery system, said method comprising: (a) blending sinterable powderwith a binder material and catalyst material, in a solvent includingwater and surfactant in order to provide a slurry mixture; (b) applyinga coating of said slurry mixture onto a current collecting material toproduce a slurry coated material; (c) drying said slurry coated materialto produce a dried article; (d) compressing said dried article to form asheet of porous flexible material; (e) sintering said sheet of flexiblematerial for a time period sufficient to remove said solvent therefromand form a sheet of flexible cathode material; (f) cutting said sheet offlexible cathode material to form a cathode belt structure having a pairof end portions; and (g) joining the end portions of said cathode beltstructure to form a virtually seamless cathode surface about a closedbelt structure.
 8. The method of claim 7, where in step (b) said currentcollecting material comprises nickel mesh or sponge material.
 9. Themethod of claim 7, where in step (a) said binder material isfluoroetheylene polymer.
 10. The method of claim 7, wherein saidsinterable powder comprises black carbon powder.
 11. The method of claim7, where in step (c) said catalyst material is magnesium dioxide (MnO₂).12. The method of claim 7, where during step (d) said dried article iscompressed so that said sheet of flexible material has a porosity in therange from about 30 to about 70%, and thickness in the range from about0.2 to about 0.6 millimeters.
 13. The method of claim 7, which furthercomprises: forming said ionically conducting medium on said sheet offlexible cathode material after step (e); or forming saidionically-conductive medium on said cathode belt structure after step(f).
 14. The method of claim 13, where after step (e) or step (f), saidionically-conducting medium comprises a solid-state film havingionically-conductive properties.
 15. The method of claim 14, where afterstep (e) or step (f), said solid-state film is gelatinous.